Fluid handling systems such as a vehicle refrigerant reconditioning system have internal scales that are used, among other things, to weigh a storage tank containing refrigerant. One way to test the scale to ensure it is calibrated is to use a weight having a known weight. To determine if a scale is calibrated, a user puts the calibrated weight on the scale and compares the reading of the scale with the known weight. Such calibration techniques may work, however, they do require an extra step of manually weighing the calibrated weight and comparing the readout on the scale with the amount of the known weight.
In addition to providing good operation of a fluid handling system, calibration of an internal scale may also be required by industry standards. For example, SAE J-2788 requires that certain refrigerant handling systems include a means for the user to verify that an internal scale is calibrated.
Accordingly, it is desirable to provide a method and apparatus that in some embodiments of the invention, permits a user to determine whether an internal scale for a refrigerant handling system is calibrated.